Backpack



FIG. 1 is a top, front, right perspective view of a backpack showing our new design;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a left side view thereof;

FIG. 5 is a right side view thereof;

FIG. 6 is a top view thereof; and,

FIG. 7 is a bottom view thereof.

The even-length broken lines and uneven-length broken lines in FIGS. 1-7 form no part of the claimed design. The zig-zag lines represent stitching. 

CLAIM The ornamental design for a backpack, as shown and described. 